Hybrid vehicle and method for controlling a transmission

Abstract

A method for controlling a transmission of a hybrid vehicle, comprising: Determining a first torque, wherein the first torque is a current required torque; Determining a second torque, the second torque being a required torque expected to be produced at a near future time after a present time; comparing, if the first torque is greater than or equal to a first threshold, the second torque with a second threshold established according to the near-future time; and Performing a downshift if, as a result of the comparison, the second torque is greater than or equal to the second threshold, wherein determining the second torque comprises: Determining a predicted value of a driver's intention to accelerate or decelerate using an acceleration or deceleration prediction model having at least one of driver tendency information, advanced driver assistance system (ADAS) information, navigation information, and vehicle speed information as an input value; and Determining the second torque using the predicted value of the intention to accelerate or decelerate, wherein the predicted value of the intention to accelerate or decelerate includes position information about the accelerator pedal and the brake pedal at the time in the near future.

Description

BACKGROUND area

[0001] The present disclosure relates to a hybrid vehicle and method of controlling a transmission therefor, and more particularly to a method of controlling a transmission capable of predicting a driver-requested torque to reduce unnecessary gear shifts and improve fuel efficiency, and a hybrid vehicle implementing the same. Discussion of related technology

[0002] An automatic transmission, a type of transmission used in automobiles or motorcycles, is capable of automatically changing the gear ratio according to the vehicle's speed or the engine's revolutions per minute (RPM). Generally, the transmission operates under the control of a transmission control unit (TCU), and a transmission with a plurality of fixed gear ratios among automatic transmissions is called a variable-ratio transmission.

[0003] The variable speed transmission shifts up when the ratio of the input speed to the output speed, that is, the ratio of the engine crankshaft speed to the input shaft speed (i.e., gear ratio), decreases.

[0004] When the vehicle is traveling at a high constant speed, the variable-ratio transmission maintains a high gear ratio for high-efficiency engine operation. The high ratio may generally be referred to as the highest ratio and / or the next highest ratio (e.g., 5-speed ratio and 6-speed ratio), and is also referred to as the cruising ratio or overdrive (OD) ratio.

[0005] In the following, with reference to Fig. 1 describes the correlation between gear ratios and efficiency.

[0006] Fig. Figure 1 illustrates a correlation between gear ratios and efficiency.

[0007] In Fig. 1, it is assumed that the 6-speed stage is the highest drive stage in the variable-stage transmission.

[0008] Referring to Fig.1, assuming that the powertrain output is maintained at a specific value, a corresponding ISO power curve 11 is plotted across the 6-speed and 5-speed gears. Furthermore, with respect to engine / drivetrain characteristics, the relative efficiency is indicated by the area of ​​ellipses in the correlation between engine torque and rpm. On the ISO power curve 11, using the 6-speed gear is more efficient than using the 5-speed gear, and accordingly, the transmission is maintained at the 6-speed gear.

[0009] When the required torque becomes higher than or equal to a predetermined value due to a driver action during high-speed driving, the variable-ratio transmission will shift to a lower ratio (in this example, 5-ratio) to meet the required torque. Generally, a separate threshold line lower than the maximum torque at a higher ratio is established to prevent the torque output from being reduced until the lower ratio is engaged. This is explained with reference to Fig. 2 described.

[0010] Fig. Figure 2 illustrates a condition under which a gear change is performed in response to a change in the required torque.

[0011] In Fig. 2 represents, in contrast to Fig.1, the horizontal axis represents the vehicle speed, and the vertical axis represents the required drive shaft torque. Furthermore, the maximum engine torque at the 5-speed stage is greater than the maximum engine torque at the 6-speed stage, and the shift threshold line corresponding to a kickdown (K / D) of the accelerator pedal by the driver (hereinafter referred to simply as the "shift threshold line") is set to be lower than the maximum engine torque at the 6-speed stage. Here, the shift threshold line can be a fixed value for each gear stage of the transmission, or it can be set to be variable according to the current vehicle speed.

[0012] When the vehicle is traveling at a constant speed, i.e., cruising speed, the 6-speed range, which has the highest efficiency, is used. However, if the required wheel torque is higher than the shift threshold (due to a driver kickdown or similar), the transmission shifts to the 5-speed range.

[0013] The demand for environmentally friendly vehicles is increasing in line with the need for continuous improvements in fuel efficiency and the tightening of emissions regulations in every country. Hybrid electric vehicles (HEVs) / plug-in hybrid electric vehicles (PHEVs) are envisioned as a practical solution to meet this demand.

[0014] Such hybrid vehicles can provide optimal output power and torque according to how the engine and motor operate in accordance with the running process, using two power sources consisting of the engine and the motor. Specifically, in a hybrid vehicle adopting a parallel-type hybrid system (or a transmission-mounted electric device (TMED) type) in which an electric motor and an engine clutch (EC) are mounted between the engine and the transmission, the output powers of both the engine and the motor can be transmitted to the drive shaft simultaneously. Of course, due to constraints such as the state of charge (SOC), it is difficult to generate engine torque all the time; however, temporary assistance of the engine output power is possible.

[0015] In the following, with reference to Fig.3 describes the correlation between the torque characteristics of the hybrid vehicle and the gear shift stages.

[0016] Fig. 3 illustrates a condition under which a gear shift is performed according to a change in required torque in a parallel type hybrid vehicle.

[0017] Referring to Fig. 3 Unlike the typical vehicle, the parallel type hybrid vehicle allows the addition of the torque of the motor to the maximum torque of the engine at each gear stage, and therefore the torque essentially transmitted to the drive shaft can be increased by the torque of the motor (motor assist range).

[0018] Nevertheless, if the general shift threshold line is set to be lower than the maximum engine torque of the corresponding stage, in a manner similar to that of Fig.2 in various situations an unnecessary gear change may occur. This is explained with reference to Fig. 4 described.

[0019] Fig. 4 illustrates a situation in which an unnecessary gear shift is caused by an operation of an accelerator pedal by a driver in a parallel type hybrid vehicle during high constant speed travel.

[0020] In Fig. 4, the horizontal axis and the vertical axis represent the time and the required torque, respectively, and it is assumed that a certain time (hereinafter referred to as the “required time for a gear change”) is taken until a gear change (ie, an actual gear change) takes place in the transmission after the TCU determines that a gear change is necessary. In addition, in Fig.4 assume that the shift threshold line is set to be lower than the maximum torque of the engine of each gear stage, and the required torque is temporarily increased due to intermittent operation of the accelerator pedal by the driver and then decreased back to the original required torque during constant speed driving at the 6-speed stage.

[0021] Referring to Fig. 4, the pattern of an increase in required torque that causes an unnecessary gear change can be generally divided into three situations.

[0022] First, situation 1 is a case where the required torque exceeds the current kickdown (K / D) shift threshold line of the current gear stage. In this situation, if a gear shift occurs, even if the required torque can be sufficiently met by the torque of the motor (ie, the amount and time of an increase in the required torque are within a range within which the motor can be used), efficiency will be reduced.

[0023] Situation 2 is a case where the required torque exceeds the engine torque limit of the current gear stage. In this situation, if a gear shift occurs, even if the required torque can be sufficiently met by the engine torque, efficiency will be reduced as in the previous case.

[0024] Situation 3 is a case where the required torque exceeds the usable range of the engine at the current gear, but the torque decreases before the actual gear shift due to insufficient time. In this situation, a gear shift is essentially unnecessary.

[0025] In the situations described above, in a typical parallel-type hybrid vehicle, slip loss or the like occurs in a gear shift preparation process, such as shift intervention and gear shifting, even though gear shifting is not necessary. This results in inefficient energy consumption.

[0026] Examples of previously known hybrid vehicles and methods for controlling a transmission therefor can be found in DE 10 2009 028 293 A1 and DE 10 2011 018 182 A1. SUMMARY

[0027] Accordingly, the present disclosure is directed to a hybrid vehicle and methods of controlling a transmission that substantially obviate one or more problems due to limitations and disadvantages of the related art.

[0028] These problems are solved by a method for controlling a transmission of a hybrid vehicle according to the features of claim 1 and / or by a hybrid vehicle according to the features of claim 7 and / or by a hybrid vehicle according to the features of claim 14. Further embodiments emerge from the dependent claims. As described, one aspect of the present invention is to provide a method for efficiently controlling a transmission in a hybrid vehicle and a vehicle for implementing the method.

[0029] In particular, one aspect of the present invention provides a transmission control method capable of determining whether or not to perform a gear shift by predicting a torque required in the near future in a parallel type hybrid vehicle, and a vehicle for carrying out the same.

[0030] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0031] To achieve these objects and other advantages of the invention as embodied and broadly described herein, a method for controlling a transmission of a parallel-type hybrid vehicle may comprise: determining a first torque, wherein the first torque is a current required torque, determining a second torque, wherein the second torque is a required torque expected to be produced at a near future time after a current time, comparing, if the first torque is greater than or equal to a first threshold, the second torque to a second threshold established according to the near future time, and performing a downshift if, as a result of the comparison, the second torque is greater than or equal to the second threshold.

[0032] In another aspect of the present invention, a parallel type hybrid vehicle may include a driving information detection unit configured to interact with various sensors of the hybrid vehicle to detect driving information according to an operation of the vehicle, a driver acceleration / deceleration prediction unit configured to generate a predicted value of a driver's near-future acceleration / deceleration intention reflecting a driving environment of the vehicle using information transmitted from the driving information detection unit by utilizing an acceleration / deceleration prediction model, a hybrid control unit configured toto determine a first torque and a second torque using the predicted value of the near-future acceleration / deceleration intention, wherein the first torque is a current required torque and the second torque is a required torque expected to be generated after a current time at a near-future time, and a transmission control unit configured to, when the first torque is greater than or equal to a first threshold, compare the second torque with a second threshold configured according to the near-future time, and to control the transmission to perform a downshift if, as a result of the comparison, the second torque is greater than or equal to the second threshold.

[0033] In another aspect of the present invention, a parallel type hybrid vehicle may include a driving information detection unit configured to interact with various sensors of the hybrid vehicle to detect driving information according to an operation of the vehicle, a driver acceleration / deceleration prediction unit configured to generate a predicted value of a driver's near-future acceleration / deceleration intention reflecting a driving environment of the vehicle using information transmitted from the driving information detection unit by utilizing an acceleration / deceleration prediction model, a hybrid control unit configured toto determine a first torque and a second torque using the predicted value of the near-future acceleration / deceleration intention, wherein the first torque is a current required torque and the second torque is a required torque expected to be generated at a near-future time after a current time; and a transmission control unit configured to send a gear change command to a transmission to perform a downshift when the first torque is greater than or equal to a first threshold. The hybrid control unit may control the transmission control unit to maintain a current transmission gear ratio.if the first torque is less than the first threshold or if, as a result of a comparison between the second torque and the second threshold, the second torque is less than a second threshold established according to the near-future time.

[0034] It is to be understood that both the foregoing general description and the following detailed description of embodiments of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate one embodiment(s) of the invention and, together with the description, serve to explain the principle of the invention. In the drawings: Fig. 1 illustrates a correlation between gear ratios and efficiency; Fig. Figure 2 illustrates a condition under which a gear change is performed in response to a change in required torque; Fig. 3 illustrates a condition under which a gear shift is performed according to a change in required torque in a parallel type hybrid vehicle; Fig.4 illustrates a situation in which an unnecessary gear change is caused by an operation of an accelerator pedal by a driver in a parallel type hybrid vehicle during high constant speed travel; Fig. 5 is a block diagram schematically illustrating a transmission control system of a hybrid vehicle according to an embodiment of the present invention; Fig. 6A and Fig. 6B illustrate an exemplary process for predicting a driver's acceleration / deceleration intention that may be applied to embodiments of the present invention; Fig. 7 illustrates a method for determining gear changes using a near-future acceleration / deceleration prediction model according to an embodiment of the present invention; Fig.8 is a flowchart illustrating a method for controlling a transmission of a hybrid vehicle according to an embodiment of the present invention; and Fig. 9 illustrates a second threshold for each time point against which a predicted required torque is compared according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Features of the present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. To clearly illustrate embodiments of the present invention in the drawings, parts not related to the description have been omitted, and like parts are designated by like reference numerals throughout the description.

[0037] Throughout this specification, when a part is referred to as "containing" an element, it is intended that the part may also contain other elements, unless specifically stated otherwise. Furthermore, parts designated by the same reference numerals throughout this specification refer to the same components.

[0038] One aspect of the present invention provides a system and method for controlling gear shifts in a hybrid vehicle having a parallel powertrain. A controller installed in a vehicle monitors a driver's input to an accelerator pedal, calculates a (current) target torque (required torque) corresponding to the driver's current pedal input (a demanded torque), and controls operation (including gear shifting) of the vehicle to provide the target torque.

[0039] Referring to Fig. 3 and Fig. 4 is in response to a pedal input (at t = t0 in Fig. 4), while the vehicle is traveling at a constant speed (the current vehicle speed in Fig.3) drives, the target torque is greater than the torque that can be generated by the engine in the current gear (6-speed stage). If the target torque is greater (Yes at S840) than the maximum torque that can be generated under the current gear (above higher stage engine + motor maximum in Fig. 3) is available at the current speed, the controller is arranged to determine whether the vehicle shifts to a lower gear (at the time t1 of a gear change determination, Fig. 4).

[0040] To prevent an unwanted gear change to a lower gear in response to an inadvertent pedal operation that will not last the minimum required time for gear changes (time required for a gear change in Fig.4), the controller estimates a future target torque for the future (estimated) driver pedal input for a future time (t2) that is at least after the minimum required time for gear changes from the time of determining a gear change (t1). In embodiments, neural networks and machine learning techniques are used to predict the future driver input and the future target torque and / or the future.

[0041] In embodiments, using the estimated future target torque (at t2), the controller (1) controls the motor to produce assist torque without shifting to a lower gear (5-speed stage) if the future target torque is greater than the maximum engine torque (without engine assist torque) of the current gear (6-speed stage) but less than the "engine + motor" maximum of the current gear, (2) causes a transition to a lower gear if the future target torque is greater than the "engine + motor" maximum of the current gear, or (3) does not control the motor to produce assist torque or does not cause a shift to a lower gear if the future target torque is less than the maximum engine torque at the current speed (or at an estimated speed at t2).

[0042] In embodiments, the controller determines whether the future target torque is greater than a threshold (threshold 2 in S850) representing an upper limit of torque below the current gear. If determined so, the controller generates signals to shift a vehicle's gear to a lower gear capable of providing the future target torque.In embodiments, the controller generates signals to shift a vehicle's gear to a lower gear only when (1) the current target torque calculated using the current pedal input for the current vehicle speed is greater than the maximum available torque under the current (higher) gear and (2) the future target torque estimated for a future time (at least after a minimum time necessary for a gear change) is also greater than the maximum available torque under the current gear.

[0043] First, with reference to Fig. 5 describes a structure of a hybrid vehicle to which embodiments of the present invention may be applied.

[0044] Fig.5 is a block diagram schematically illustrating a transmission control system of a hybrid vehicle according to an embodiment of the present invention.

[0045] Referring to Fig. 5, the system 100 for switching the driving mode of a hybrid vehicle according to an embodiment of the present invention includes a driving information detection unit 110, a driving style determination unit 120, a driver acceleration / deceleration prediction unit 130, and a hybrid control unit 140. This configuration is only illustrative, and the transmission control system can be designed to include fewer elements (e.g., omitting the driving style determination unit) or more elements.

[0046] The driving information detection unit 110 detects driving information corresponding to a travel of the vehicle in operative connection with at least one of a vehicle speed sensor 11, an accelerator pedal position sensor (APS), a brake pedal sensor (BPS) 13, an advanced driver assistance system (ADAS) 14, and a navigation unit 15.

[0047] The driving information detection unit 110 detects the status of an accelerator pedal operation by the driver via the APS 12 and detects a brake operation status via the BPS 13.

[0048] The driving information detection unit 110 detects the vehicle speed via the vehicle speed sensor 11 and detects information about the behavior ahead, including the relative distance and acceleration with respect to a preceding vehicle, via a radar sensor, a (stereo) camera, or the like of the ADAS 14. Of course, in addition to the radar and the camera, various sensors such as an ultrasonic sensor and laser can be used depending on the design of the ADAS.

[0049] The driving information detection unit 110 detects navigation information (road environment information), such as GPS / GIS-based location information about the vehicle, road type, congestion gradient, speed limit, intersection, toll booth, curve, and gradient information. To provide this information, the navigation unit 15 may reference an integrated navigation map and traffic information collected via external wireless communication (e.g., telematics, TPEG, etc.).

[0050] The driving style determination unit 120 determines a driver's driving style based on a driving pattern such as an average speed, an APS change amount (dAPS), and a BPS change amount (dBPS) according to the driver's handling of the vehicle.

[0051] For example, the driving style determination unit 120 may configure a fuzzy membership function using measurement factors such as the APS change amount, the BPS change amount, the vehicle speed, the gradient, and the like detected by the driving information detection unit 110 as input parameters, and calculates a short-term driving style index (SI = 0 to 100%).

[0052] The driving style determination unit 120 can determine the driver's driving style in a variety of levels by dividing the calculated short-term driving style index (SI = 0 to 100%) based on a predetermined reference ratio according to the driving style intensity.

[0053] The driver acceleration / deceleration prediction unit 130 learns an acceleration / deceleration prediction model according to the driving style using a machine learning scheme, and provides a predicted value of the driver's near-future acceleration / deceleration intention reflecting the vehicle's driving environment and driving style by using the acceleration / deceleration prediction model. That is, the driver acceleration / deceleration prediction unit 130 can use the vehicle speed, radar information, navigation information, and driver's driving style detected by the driving information detection unit 110 as input information to quantitatively digitize the type of driving manipulation that occurs in units of a relatively short time.This allows the driver acceleration / deceleration prediction unit 130 to determine a driver's current acceleration / deceleration intention and generate a predicted near-future acceleration / deceleration value by the driver. The predicted acceleration / deceleration value can be configured with a magnitude and probability of depressing an accelerator pedal or brake pedal in a predetermined unit of time in the near future.

[0054] A specific prediction algorithm of the acceleration / deceleration prediction unit 130 may comprise a neural network that supplements a previously constructed prediction model using a machine learning technique, which will be described in more detail later.

[0055] The hybrid control unit 140 controls the operation of each part for switching the traveling mode of the hybrid vehicle according to an embodiment of the present invention, and integrally controls, as the highest control unit, the engine control unit and the motor control unit connected via a network.

[0056] The hybrid control unit 140 can analyze a current driver demand torque detected by the driving information detection unit 110 via the APS or BPS and send the analyzed torque to the TCU. Furthermore, the hybrid control unit can predict a demand torque at a specific time in the near future based on the received predicted value of near-future acceleration / deceleration and send the predicted torque to the TCU.

[0057] The TCU may obtain information about the current required torque and the predicted near-future required torque value from the hybrid control unit 140 to determine whether or not to perform a gear shift and send a gear shift command to the transmission according to the determination result.

[0058] In some embodiments, if the acceleration / deceleration prediction unit 130 even predicts the near-future required torque using the predicted near-future acceleration / deceleration value, the acceleration / deceleration prediction unit 130 may send the near-future required torque value directly to the TCU.

[0059] Alternatively, the TCU may determine whether or not to perform a gear shift based on the current required torque, and the hybrid control unit 140 may determine whether or not to perform a gear shift based on the predicted value of the near-future required torque. The result of the determination made by the hybrid control unit 140 may be sent to the TCU to override the TCU's gear shift determination.

[0060] In this embodiment, the driving style determination unit may be omitted depending on the configuration. In this case, the driver acceleration / deceleration prediction unit 130 may perform acceleration / deceleration prediction excluding an input value related to the driving style.

[0061] In the following, with reference to Fig. 6A and Fig.6B, a method for the driver acceleration / deceleration prediction unit 130 to predict the driver's acceleration / deceleration intention is described.

[0062] Fig. 6A and Fig. 6B illustrate an exemplary process for predicting a driver's acceleration / deceleration intention that may be used for embodiments of the present invention.

[0063] Referring to Fig.6A, the process of the driver acceleration / deceleration prediction unit 130, which predicts the driver's acceleration / deceleration intention, can be divided into three steps. Specifically, parameters to be used as input parameters for prediction can be determined first (S61). The prediction model can be modified by a machine learning scheme (S62), and the acceleration and deceleration can be classified by the determined input value and the modified model to calculate a predicted value for a near-future situation (S63).

[0064] Determining the input value (S61) here may include: 1) extracting candidate input values; 2) preprocessing input signals by integrating the input signals; and 3) selecting a final parameter using the preprocessed candidate values. As a machine learning scheme, a time series model-based technique or a deep learning-based technique may be used. Examples of the time series model-based technique may include the autoregressive integrated moving average (ARIMA) technique, which describes changes in behavior over time with a stochastic indicator, and the multilayer perceptron (MLP) technique, which uses nonparametric regression as a universal approximator.Examples of deep learning-based techniques include the stacked auto-encoder (SAE) technique, which makes input / output data similar through dimensionality reduction, the recurrent neural network (RNN) technique, which is a neural network algorithm for processing sequential information, and the long short-term memory (LSTM) technique, which is suitable for learning long-term dependency. An example of the driver acceleration / deceleration prediction unit, which predicts the driver's near-future acceleration / deceleration intention using the neural network algorithm, is shown in [1]. Fig. 6B.

[0065] Referring to Fig.6B, the driver acceleration / deceleration prediction unit 130 according to an embodiment of the present invention includes a neural network that learns an acceleration / deceleration prediction model for each driver driving style using a machine learning technique.

[0066] The driver acceleration / deceleration prediction unit 130 preferably includes a near-future acceleration / deceleration prediction model for each driving style, which model is preconstructed based on large amounts of data accumulated through test drives using the neural network before delivery of the vehicle.

[0067] Furthermore, the driver acceleration / deceleration prediction unit 130 may reflect the vehicle behavior data learned through actual vehicle driving after vehicle delivery in the near-future acceleration / deceleration prediction model for each driving style constructed using the neural network, thereby generating a near-future acceleration / deceleration prediction model for each driving style that is personalized for the driver. At this time, the driver acceleration / deceleration prediction unit 130 may apply the learned behavior data to the near-future acceleration / deceleration prediction model of the corresponding driving style according to a determination of the driver's driving style (gentle, general, sporty, etc.).

[0068] The driver acceleration / deceleration prediction unit 130 can calculate a predicted value of the near-future acceleration / deceleration intention according to the driver's driving style by utilizing the driving environment including the vehicle speed, radar information, and navigation information, and the driver's driving style as input information. Here, the driving style can be classified into a variety of style types as shown in Fig. 6B and can be set up by numerical values ​​such as an average speed, a rate of change of the accelerator pedal (dAPS) and a rate of change of the brake pedal (dBPS).

[0069] In addition, the driver acceleration / deceleration prediction unit 130 may perform model modification according to the driver acceleration / deceleration model that learns through a real-time machine learning scheme while mounted on the vehicle, or may receive a modified model from the outside and use it for the prediction operation without learning.

[0070] In other words, if the model is allowed to be modified externally, the parameters serving as input values ​​for learning can be sent to a telematics center or a cloud server, so that model modification is performed by external learning and only a final model is transmitted to the vehicle.

[0071] Fig.7 illustrates a model for determining a gear shift using a near-future acceleration / deceleration prediction model according to an embodiment of the present invention.

[0072] Referring to Fig. 7, the hybrid control unit 140 according to an embodiment of the present invention analyzes current operating requirements according to the driver's operation of the APS or BPS, calculates a required torque, and sends the calculated torque to the TCU (S1). The TCU determines whether to perform a gear shift based on whether the current required torque is higher than the shift threshold line variably set according to the vehicle speed (S2).

[0073] The TCU may then additionally apply the predicted required torque value according to the driver's acceleration / deceleration intention prediction information using the near-future acceleration / deceleration prediction model in the driver acceleration / deceleration prediction unit 130 to the gear shift determination result based on the current required torque and the transmission threshold line, and finally determine whether to perform a gear shift (S3). Depending on the determination result, the TCU may send a gear shift command to the transmission. Here, the predicted required torque value may be calculated by the driver acceleration / deceleration prediction unit 130 or may be calculated by the hybrid control unit 140.Although not shown in the figure, the predicted required torque value may be calculated by a separate control unit for generating the predicted required torque value.

[0074] The method for switching the driving mode for the hybrid vehicle according to an embodiment of the present invention will be described with reference to Fig. 8, focusing on the system 100 for switching the driving mode of the hybrid vehicle described above.

[0075] Fig. 8 is a flowchart illustrating a method for controlling a transmission of a hybrid vehicle according to an embodiment of the present invention.

[0076] Referring to Fig.8, the hybrid control unit first detects the APS change amount or the BPS change amount via the driving information detection unit 110 and calculates the current driver demand torque (S810). The calculated demand torque can be sent to the TCU.

[0077] The required torque can be obtained here from a function of the pedal position Pedal(n), which is detected by the current pedal sensors APS and BPS. Specifically, '(n)' has a positive (+) value when the accelerator pedal APS is depressed and a negative (-) value when the brake pedal BPS is depressed.

[0078] If the APS and BPS are detected simultaneously due to the driver's faulty manipulation, the hybrid control unit can apply the brake override function to ignore the APS change and calculate the required torque based only on the BPS change.

[0079] Meanwhile, the driver acceleration / deceleration prediction unit 130 generates a predicted value of the driver's near-future acceleration / deceleration intention using the vehicle speed, radar information, navigation information, and the driver's driving style as input information (S820). Here, pedal(n+a) means the position of the accelerator / brake pedal after 'a' seconds. The value of a is preferably less than 5 seconds; but embodiments of the present invention are not limited thereto. In addition, the predicted value of the near-future acceleration / deceleration intention may mean the driver's acceleration intention (APS increase or BPS decrease) or deceleration intention (APS decrease or BPS increase) predicted after a predetermined time in the near future, and its change amount, or the pedal position.

[0080] Using the predicted value of the acceleration / deceleration intention Pedal(n+a) of the driver acceleration / deceleration prediction unit 130, the hybrid control unit can predict the torque required in the near future and send the predicted torque to the TCU (S830).

[0081] The TCU may compare the current required torque sent from the hybrid control unit with a first threshold (S840). Here, the first threshold is preferably a shift threshold line.

[0082] If the current required torque is greater than or equal to the first threshold, the TCU may compare the predicted required torque with a second threshold (S850). Here, the second threshold may be set differently according to the prediction time and will be described later with reference to Fig. 9 described in detail.

[0083] If the predicted required torque is greater than the second threshold, the TCU may determine a downshift and send a gear change command to the transmission (S860).

[0084] If the current required torque is less than the first threshold or the predicted required torque is less than the second threshold, the current gear stage may be maintained (S870). At this time, in order to satisfy the required torque while maintaining the gear stage according to the current required torque, if the current required torque exceeds the maximum engine torque of the corresponding stage, the hybrid control unit may send a torque command to instruct the motor control unit to generate a sufficient amount of torque to compensate for the insufficient torque.

[0085] In the following, with reference to Fig. 9 the second threshold is described.

[0086] Fig. 9 illustrates a second threshold for each time point against which a predicted required torque is compared according to an embodiment of the present invention.

[0087] Referring to Fig. 9, the second threshold may be one of 1) the sum of the maximum higher-level engine torque and the maximum motor torque, 2) the maximum higher-level engine torque, and 3) the shift threshold line (assuming a non-hybrid vehicle or no motor assistance in a hybrid vehicle). For example, if the time is in the near future ( Fig.9, Prediction time 1) is within a time required for shifting from the time of determining a gear change (the current time), the sum of the maximum higher-stage engine torque and the maximum motor torque may be the second threshold. If the prediction time is in the near future within a first predetermined time after the time required for shifting ( Fig. 9, Prediction Time 2), the maximum engine torque of the higher stage may be the second threshold. If the prediction time is in the near future within a second predetermined time after the first predetermined time ( Fig. 9, prediction time 3), the switching threshold line can be the second threshold.

[0088] However, the criterion and time range for the second threshold for each near-future prediction time point described above are illustrative, and embodiments of the present invention are not limited thereto. Those skilled in the art will appreciate that the second threshold can be set to different values ​​for more or fewer prediction times.

[0089] In the embodiments described above, the model for predicting a driver's acceleration / deceleration intention was described as being constructed and modified by a machine learning scheme of the driver's future intention according to the current driving condition based on the data accumulated during actual driving of the vehicle. However, instead of using such a prediction model, the predicted value of the near-future acceleration / deceleration intention may be determined by establishing a rule in advance. An example of such a rule is shown in Table 1 below. TABLE 1 Input signal Analysis of the driving situation Expected result [Sat / Telematics] Road type = Motorway Traffic jam information = smooth Event ahead = no Driving at a constant speed Intermittent braking to reduce the distance to the APS = 0, BPS = Small [Radar] Distance to the vehicle in front = close Relative speed of the vehicle in front = -10 km / h vehicle in front [Driving style / history] Driving at a constant speed for the last 5 minutes [Lane Keeping System] Maintain current lane [Navigation / Telematics] Road type = Motorway Traffic jam information = smooth Event ahead = Toll station / 200m Motorway journey Pass toll station, reduce current speed to 50 km / h APS = 0, BPS = medium [Radar] Distance to the vehicle in front = none Relative speed of the vehicle in front = N / A [Driving style / history] After passing the toll booth, average vehicle speed = 50 km / h [Lane Keeping System] Maintain current lane

[0090] Further, although the future required torque was described above as being predicted via a near-future forecast, it may be replaced by an expected future acceleration value predicted by the acceleration / deceleration prediction unit. Also, the second threshold may be set to an acceleration value instead of the required torque. As a result, if the current required torque is greater than or equal to the first threshold and the predicted acceleration at a time in the near future is greater than or equal to the second threshold represented by an acceleration, a downshift may be performed; if not, the current gear ratio may be maintained.

[0091] One aspect of the present invention described above can be implemented as computer-readable code on a medium on which a program is recorded. The computer-readable medium includes all types of recording devices in which data readable by a computer system is stored. Examples of the computer-readable medium include a hard disk drive (HDD), a solid-state drive (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, and an optical data storage device.

[0092] As is apparent from the above description, embodiments of the present invention exhibit the following effects.

[0093] A hybrid vehicle relating to at least one embodiment of the present invention configured as described above can control the transmission more efficiently.

[0094] In particular, unnecessary gear shifts can be minimized because whether or not to perform a gear shift is determined by predicting the required torque in the near future using a machine learning scheme and comparing it with a reference threshold over time. As a result, energy consumption during the gear shift process can be reduced, and an improvement in on-road fuel efficiency can be expected.

[0095] Logical blocks, modules, or units described in connection with embodiments disclosed herein may be implemented or executed by a computing device having at least one processor, at least one memory, and at least one communication interface. The elements of a method, process, or algorithm described in connection with embodiments disclosed herein may be embodied directly in hardware, in a software module executed by at least one processor, or in a combination of the two. Computer-executable instructions for implementing a method, process, or algorithm described in connection with embodiments disclosed herein may be stored in a non-transitory computer-readable storage medium.

[0096] Those skilled in the art will appreciate that effects of embodiments of the present invention are not limited to what has been described above, and other effects of the present invention will be clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

[0097] Those skilled in the art will recognize that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, the present disclosure is intended to cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

[1] A method for controlling a transmission of a hybrid vehicle, comprising: Determining a first torque, wherein the first torque is a current required torque; Determining a second torque, the second torque being a required torque expected to be produced at a near future time after a present time; comparing, if the first torque is greater than or equal to a first threshold, the second torque with a second threshold established according to the near-future time; and Performing a downshift if, as a result of the comparison, the second torque is greater than or equal to the second threshold, wherein determining the second torque comprises: Determining a predicted value of a driver's intention to accelerate or decelerate using an acceleration or deceleration prediction model having at least one of driver tendency information, advanced driver assistance system (ADAS) information, navigation information, and vehicle speed information as an input value; and Determining the second torque using the predicted value of the intention to accelerate or decelerate, wherein the predicted value of the intention to accelerate or decelerate comprises position information about the accelerator pedal and the brake pedal at the time in the near future. [2] The method of claim 1, further comprising: Maintaining a current transmission gear if, as a result of the comparison, the first torque is less than the first threshold or if the second torque is less than the second threshold. [3] The method of claim 1 or 2, wherein determining the first torque comprises: Determining positions of an accelerator pedal and a brake pedal; and Determine the first torque using the determined positions. [4] The method of claim 1, wherein the model for predicting acceleration or deceleration is continuously modified by machine learning-based learning. [5] A method according to any one of the preceding claims, wherein the second threshold is determined as one of the first threshold, a maximum engine torque corresponding to a current transmission gear stage, and a sum of the maximum engine torque and a maximum motor torque depending on the near-future time. [6] Method according to one of the preceding claims, further comprising: Generating a third torque in an engine when the current transmission gear ratio is maintained and the first torque exceeds a maximum engine torque corresponding to the current transmission gear ratio by the third torque. [7] Hybrid vehicle, comprising: a driving information detection unit configured to interact with various sensors of the hybrid vehicle to detect driving information according to an operation of the vehicle; a driver acceleration or deceleration prediction unit configured to generate a predicted value of a driver's near-future acceleration or deceleration intention reflecting a driving environment of the vehicle using information transmitted from the driving information detection unit by utilizing an acceleration or deceleration prediction model; a hybrid control unit configured to determine a first torque and a second torque using the predicted value of the near-future acceleration or deceleration intention, wherein the first torque is a current required torque and the second torque is a required torque expected to be generated at a near-future time after a current time; and a transmission control unit configured to compare, when the first torque is greater than or equal to a first threshold, the second torque with a second threshold configured according to the near-future time, and to control a transmission to perform a downshift if, as a result of the comparison, the second torque is greater than or equal to the second threshold, wherein the driver acceleration or deceleration prediction unit generates the predicted value of the acceleration or deceleration intention using the acceleration or deceleration prediction model with at least one of driver tendency information, advanced driver assistance system (ADAS) information, navigation information, and vehicle speed information as an input value, and wherein the predicted value of the intention to accelerate or decelerate comprises position information about an accelerator pedal and a brake pedal at the time in the near future. [8] A hybrid vehicle according to claim 7, wherein a transmission control unit performs a control operation to maintain a current transmission gear stage when, as a result of the comparison, the first torque is less than the first threshold or when the second torque is less than the second threshold. [9] A hybrid vehicle according to claim 7 or 8, wherein the hybrid control unit determines the first torque using positions of an accelerator pedal and a brake pedal detected by the driving information detection unit. [10] A hybrid vehicle according to claim 7, wherein the model for predicting acceleration or deceleration is continuously modified by machine learning-based learning. [11] A hybrid vehicle according to any one of claims 7 to 10, wherein the first threshold value is variable according to a speed of the vehicle and is set to be lower than a maximum engine torque corresponding to a current transmission gear stage. [12] A hybrid vehicle according to any one of claims 7 to 11, wherein the second threshold value is determined as one of the first threshold value, a maximum engine torque corresponding to a current gear stage, and a sum of the maximum engine torque and a maximum motor torque depending on the near future time. [13] A hybrid vehicle according to any one of claims 7 to 12, wherein, when the current transmission gear stage is maintained and the first torque exceeds a maximum engine torque corresponding to the current transmission gear stage by the third torque, the hybrid control unit sends a torque command to the engine control unit to generate the third torque via the engine. [14] Hybrid vehicle, comprising: a driving information detection unit configured to interact with various sensors of the hybrid vehicle to detect driving information according to an operation of the vehicle; a driver acceleration or deceleration prediction unit configured to generate a predicted value of a driver's near-future acceleration or deceleration intention reflecting a driving environment of the vehicle using information transmitted from the driving information detection unit by utilizing an acceleration or deceleration prediction model; a hybrid control unit configured to determine a first torque and a second torque using the predicted value of the near-future acceleration or deceleration intention, wherein the first torque is a current required torque and the second torque is a required torque expected to be generated at a near-future time after a current time; and a transmission control unit configured to send a gear change command to a transmission to perform a downshift when the first torque is greater than or equal to a first threshold, wherein the hybrid control unit controls the transmission control unit to maintain a current transmission gear stage when the first torque is less than the first threshold or when, as a result of a comparison between the second torque and the second threshold, the second torque is less than a second threshold established according to the near-future time point, wherein the driver acceleration or deceleration prediction unit generates the predicted value of the acceleration or deceleration intention using the acceleration or deceleration prediction model with at least one of driver tendency information, advanced driver assistance system (ADAS) information, navigation information, and vehicle speed information as an input value, and wherein the predicted value of the intention to accelerate or decelerate comprises position information about an accelerator pedal and a brake pedal at the time in the near future.

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